John mullaly



eg t 3155;, PATENT O F I i", J I

- l to'w u w JOHN MULLALY, OF'NE'W YORK, N, Y. y

PROCESS OF PREPARING SU RFACE-PRINTING PLATES.

SPECIFICATION forming part of Letters Patent No. 522,719, dated July 10,1894.

Application filed June 13,1893. Serial No.477. 482. (N specimens.) I r i5 I e T0 all whom i may concern: former. In fact the difficulty ofprocuring I Be it known that I, JOHN MULLALY, a citisufiiciently purealuminium commercially, zen of the United States, residing in the city,and the cost of the same, render my process l county, and State of NewYork, have invented of eliminating the impurities from the surface p 5certain new and useful Improvements in Proof a plate in which aluminiumpredominates cesses of Preparing Surface-Printing Plates, of especialimportance in the art. of which the following is a description, suffi-In carrying out my invention I form the .cient to enable others skilledin the art to surface printing plate from a suitable (luau 6 which theinvention appertains to use the tity of aluminium, procured commerciallyor to same. otherwise, in the usual manner. After the My improvementsrelate especially to the plate is in shape I treat the SllIfl0Q ;11p0Hclass of surface printing plates set forth in the which the design is tobe imposed to a washpatents issued to John Mullaly and Lathrop or bathof a dilute acid having little or no L. Bullock, No. 459,239, ofSeptember 8, I891, affinity for aluminium,a s nitric, or other acid, I5No. 476,759, of June 7, 1892, and No. 483,498, which will attack theiron and'bther impuri- V of September 27, 1892, in which the essentialties ordinarily permeating common alumiuifeature consists in forming theplate mainly um, combining with them so that they'may v of aluminium- Inorder to attain the best rebe washed out and away without aifecting thesults with these aluminium surface printing pure aluminium. Thistreatment with acid. 20 plates it is desirable that the aluminium be maybe resorted to either before or after the practically free fromimpurities, especially graining of the plate, but must be prior to the Vi those which oxidize readily, and difficulty has impiiition of thedesign otherwise the latter l been experienced in procuring sufficientlywill be injured by the acid. Iprefer however 5 pure metal, certainimpurities developing to grain thesurface of the platebefore elimii 25specks upon the plate during its manipulamating the surface impuritiessince the opera-[. 1

- tion which were apt to take the ink and so tion of graining cXp2QSthesurface impuri- E 7 mar the impression taken from the surface of tiesmore effectually to the action of the acid i s the plate. After carefulinvestigation and without impairing the grained surface.

experiment I have devised a method of ob- I am aware that acids haveheretofore been 3 Viating this difiiculty, and my invention conused inconnection'with printing surfaces for 'sists essentially in removing theimpurities the purpose of etching the stone or plateitself. 1; '1 at thesurface of the plate, prior to the im- The object sought and attained bymy invenposition'of the design to be printed theretion is just thereverse of this. I purposely from, by means of an acid against which theemploy an acid that will not affect the alualuminium itself is proof. Bythis means I. miniurmbu w1 attack various impuriam enabled to prepareand use successfully tieseix posed'i nfiie spraceo comm rcla y andcontinuously in surface printing an alunlifniii'm 'a'fi'dfembvethem'without'disturbing I V minium plate that would otherwise be uselessor impairing the surface of the aluminium on go for the purpose onaccount of impurities. which .the design is to be imposed. There isAbsolutely pure aluminium is an article diftino etching of the plateitself; by my inven- I cult to obtain commercially, so that by overtionI have simply rendered what is known as ,7 1 coming'the objection to theuse of the inferior commercial algpjnigm, as distinguished from v orcontaminated aluminium obtainablein the laboratory or chemically purealuminium, market,Inot only perfect but also cheapen the suitable forsurface printing by quickly and surface printing plate, while attainingresults cheaply removing from the surface thereof I that are morecertain and uniform in so far as the exposed impurities that wouldotherwise theprintsare concerned. Thusby myprocess takethe-ink andimpair the prints taken an inferior grade ofalurninium may be usedtherefrom. p

loo 1 p 1 in the formation of a surface printing plate In carryingout'my invention Ihave found f 5o and made to give as good results as aplate that nitric acid, diluted with ten to twenty per; j .made frompractically pure aluminium,which cent. of water, is convenient andefiective in. 1 latter would cost several times the price of thetreating the plates, The strength of the solution, and the length oftime in which the plate 1s subjected to the action of the acid solutronvary with the grade of aluminium under treatment, there being severalcommercial grades of the metal. The purification of the prlnting surfaceis eifected by either spreadng the acid solution over such surface or bylnimersing the plate bodily in the solution, the surface being exposedto the action for several hours, sometimes for twenty-four, if the plateis of low grade.

What I claim as my invention, and desire to secure by Letters Patent,is-

The process herein set forth of preparing aluminium plates for use insurface printing, consisting in subjecting the surface upon which thedesign is to beimposed to the action of an acid which will not affectthe aluminium but which will attack the exposed impurities so that theymay be removed prior to the imposition of the design substantially inthe manner and for the purpose described.

- JOHN MULLALY.

Witnesses:

GEORGE WILLIAM MIATT, D. W. GARDNER.

